Key points to remember

• Flecainide is given to control and prevent abnormal heart rhythms.
  
• It is important to attend all appointments with your child’s cardiologist so your child’s condition can be monitored.
  
• Your child’s dose of flecainide may need to change over time – always follow the directions given to you by your child’s doctor.
• Separate doses of flecainide from milk (including breast milk and infant formula) and dairy products.
  
• Contact your doctor or hospital immediately if your child has chest pain, shortness of breath or any signs of an allergic reaction.

Flecainide (flek-an-ide) is a medicine that can control and prevent abnormal heart rhythms (arrhythmia).

Flecainide is produced and sold by many different companies, and different brands of the same medicine have different names (e.g. Tambocor, Flecatab).

Giving your child flecainide

Your child’s doctor will work out the amount (the dose) of flecainide that is right for your child. The dose will be shown on the medicine label. It is important to give your child this medicine exactly as instructed as it can be dangerous if given incorrectly.

Flecainide is usually started at a low dose and slowly increased until your child’s condition is controlled. Your child’s cardiologist (heart specialist) will schedule regular appointments to monitor your child’s condition and to make sure the flecainide is working. It is important you attend every appointment, so your child’s doctor can adjust the dose if needed.

Flecainide is available as 50mg and 100mg tablets. The Royal Children’s Hospital (RCH) pharmacy department also prepare capsules in a range of strengths for patients who have a prescription written by an RCH doctor. Your child’s doctor or pharmacist will advise which product is most suitable for your child. Flecainide should not be prepared by a compounding pharmacy.

When should I give flecainide?

Flecainide is usually given two or three times per day, as directed by your doctor.

It is important to give flecainide around the same time each day so it becomes part of your daily routine. If more than one person usually gives your child their medication, make sure that you communicate and write down doses given so that you don’t give extra doses by mistake.

• Flecainide tablets can be swallowed whole or halved if needed and taken with a glass of water. If your child is unable to swallow tablets, they can be dissolved in a small amount of water.
• Flecainide capsules can be swallowed whole with a glass of water. If your child is unable to swallow capsules, they may be opened and the contents mixed with a small amount of water.

Separate doses of flecainide from milk (including breastmilk and infant formula) or dairy foods:

• Wait at least 60 minutes (either side of dose) before giving milk or dairy products to children under two years.

• Wait at least 30 minutes (either side of dose) before giving milk or dairy products to children over two years.

What to do if a dose is missed

You should discuss what to do in the event of a missed or late dose with your child’s cardiologist or pharmacist before leaving hospital. You can ask them to provide you with a written action plan to take home and follow if a dose has been missed. Never give a double dose of flecainide to make up for a missed dose as this can cause changes to your child’s heart rhythm.

What to do if you give too much flecainide

It can be dangerous if too much flecainide is given. If you think you may have given your child too much flecainide, call the Poisons Information Centre on 13 11 26 as soon as possible, even if your child shows no symptoms. In the case of an emergency, call an ambulance (000) or take your child to the nearest hospital emergency department. Have the medicine container or packaging with you, even if it is empty, as this information will be useful.

Possible side effects

Medicines are designed to make us better, but sometimes they have unwanted effects (side effects). Some side effects will go away with time, or after the dose has been changed. If your child is vomiting or has diarrhoea or they have not eaten for more than 24 hours, this may increase the chance of side effects from flecainide – contact your child’s cardiologist for advice in this situation.

Speak to your child’s doctor if you are worried about any of the following:

• blurred vision or seeing spots
  
• dizziness
  
• anxiety
  
• constipation
  
• headache
  
• nausea and vomiting.
  

Your child may feel dizzy while taking flecainide. Care must be taken with activities like bike riding or climbing, or, for older children, driving or operating heavy machinery.

Contact your doctor or hospital immediately if your child has:

• chest pain or palpitations
  
• shortness of breath
  
• a tremor
  
• yellowing of the whites of the eyes or skin
  
• any signs of an allergic reaction (e.g. skin rash or swelling of the lips, mouth or throat).
  

There may be other side effects that are not listed in this fact sheet. If you notice anything unusual or are concerned about your child, contact your doctor.

General medicine advice

• Give flecainide only as directed and only to the person who the medicine was prescribed for. Never give it to another person, even if their condition appears to be the same, as this could do harm.
• If your child requires surgery, you must tell the anaesthetist that your child is taking flecainide.
• Store flecainide tablets and capsules at room temperature, in a cool, dry place away from heat or direct sunlight, below 25 degrees Celcius.
  
• Store all medicines out of reach of children and always keep medicine in the container or box that it came in.

For more information

This fact sheet has been developed to provide practical advice about the use of this medication in children and should be read in addition to the information supplied by the manufacturer which can be found at NPS MedicineWise

• Talk to your doctor or pharmacist
• Kids Health Info fact sheet: Medicines for children and medicine reactions
• The Therapeutic Goods Administration: Consumers

Developed by The Royal Children's Hospital Pharmacy and Cardiology departments. We acknowledge the input of RCH consumers and carers.

Reviewed December 2024.

Please always seek the most recent advice from a registered and practising clinician.